IMAGES OF ASTROPHYSICAL MASERS AND THEIR VARIABILITY IN A TURBULENT MEDIUM: THE 25 GHz METHANOL MASERS

摘要

We examine the influence of chance coherences in turbulent velocities for the creation of the images of astrophysical masers. Images are computed that represent the numerous masing features that are commonly observed in an extended masing region. Changes as a function of Doppler velocity can be seen in the appearance of these images. Variability in the images also is evident as a result of the evolution of the turbulent velocities with time. Representative turbulent velocity fields are obtained by standard methods involving the statistical sampling of Fourier components, and the medium is treated as incompressible for computing the time evolution of the turbulence. Comparisons with observational data focus on the 25 GHz methanol masers, for which there is evidence that their structure may be caused mainly by coherences in the velocities.